The present invention relates generally to antennas, and more particularly, to a common aperture isolated dual frequency band antenna.
Space for antennas is typically a premium on missiles, and other airframes. When two antennas are in close proximity and one antenna is used to transmit while the other is simultaneously used to receive, the transmitting antenna can overload the receiver of the receiving antenna causing the system to malfunction, or be destroyed. This problem is conventionally overcome by placing the antennas further apart or by blanking the receive antenna while the other one transmits. This is costly and makes for a more complicated system than may be desired.
One prior art antenna form used in this situation involves the use of two opposite sense spiral antennas. The disadvantage of this antenna configuration is that there are two antennas that take up a relatively large amount of area, roughly twice the area as the present invention. Another antenna form is a sinuous spiral antenna that receives both senses at the same time. The drawback with the sinuous spiral antenna is that it cannot simultaneously receive the two signals at the different frequencies and separate them into different channels of a receiver. Therefore, there is no isolation of the two signals.
Accordingly, it is an objective of the present invention to provide for a common aperture isolated dual frequency band antenna. It is another objective of the present invention to provide for an antenna that simultaneously provides for transmission and reception of two different frequencies in relatively compact package, and that isolates these two different frequencies from each other.